1. Field of the Invention
The present invention relates to an image processing apparatus and a computer program product.
2. Description of the Related Art
Conventionally, an ultrasonic diagnostic apparatus is used in a medical practice of today for an examination of and a diagnosis on various living body tissues, such as a heart, a liver, a kidney, and a mammary gland, as an apparatus that has advantages, such as simple to operate, noninvasive, and without risk of radiation exposure, compared with other medical image diagnostic apparatuses, for example, an X-ray diagnostic apparatus, and an X-ray Computed Tomography (CT) apparatus.
An ultrasonic diagnostic apparatus transmits an ultrasonic wave from an ultrasonic probe, and receives an ultrasonic wave reflected from internal tissue of a subject, thereby creating a tomogram (B-mode image) of histology inside the subject in real time. Furthermore, the ultrasonic diagnostic apparatus creates blood-flow information as a Doppler image in real time by using the Doppler effect of ultrasonic waves, the blood-flow information including, for example, an area in which a blood flow is present inside a subject, and the velocity, dispersion (disturbance in the blood flow) and power (diffusion strength of the blood flow) of the blood flow.
Recently, an ultrasonic diagnostic apparatus has come into practical use, which creates a three-dimensional ultrasonic image in real time by scanning three-dimensionally the inside of a subject by using a two-dimensional array transducer ultrasonic probe. The ultrasonic diagnostic apparatus that performs a three-dimensional scan can collect in real time, for example, a B-mode image of three-dimensional histology of a heart that is beating time-sequentially, and can display the B-mode image.
When displaying the three-dimensional B-mode image, a method of volume rendering is used. For example, the histology of a heart includes a heart wall and a heart valve to be depicted with high brightness in a B-mode image, and a heart cavity of which almost all part of the inside is to be depicted in black. Accordingly, by volume-rendering a half of the heart as a display subject region, a stereoscopic image of the heart wall and/or the heart valve viewed from the inside of the heart cavity can be displayed. By referring to a stereoscopic image of a half of a heart that is volume-rendered, a doctor can efficiently diagnose a disease in a heart valve or a heart wall, or congenital anomaly in the heart valve or the heart wall.
The ultrasonic diagnostic apparatus that performs a three-dimensional scan can simultaneously collect three-dimensional information about a blood flow with three-dimensional information about histology by using the Doppler effect, and can display a three-dimensional blood-flow distribution by performing volume rendering on a three-dimensional Doppler image.
For example, when performing volume rendering on a three-dimensional Doppler image, three-dimensionally highlighted turbulence in a blood flow can be rendered by using dispersion of blood-flow velocities in blood-flow information (for example, see JP-A 2007-296333 (KOKAI)), accordingly, a turbulent blood flow caused by anomaly in a hear wall or a heart valve can be clearly displayed.
According to the above conventional technology, there is a problem that a blood flow cannot be displayed in three dimensions in a format suitable for diagnosis.
For example, blood is filled in a heart cavity of the heart, and the velocity of a blood flow continuously changes, as a result, a region in which the blood flow is present does not have clear border. For this reason, when performing volume rendering on a three-dimensional Doppler image, the blood flow cannot be stereoscopically displayed.
For a doctor to perform diagnosis efficiently, information about histology is needed simultaneously with blood-flow information; however, if a three-dimensional B-mode image on which volume rendering is performed is displayed in a superposed manner over a three-dimensional Doppler image on which volume rendering is performed, histology behind a blood flow is hidden. For this reason, the information about histology cannot be clearly displayed along with the blood-flow information.
As described above, according to the conventional technology, although a turbulent blood flow caused by anomaly in a heart valve or a heart wall can be clearly displayed, three-dimensional information about the blood flow cannot be displayed in a format suitable for diagnosis as well as three-dimensional information about histology.